Vehicles such as pickup trucks are equipped with a cargo bed and typically an open cargo box formed by walls extending vertically from the bed. The primary purpose of the pickup truck bed and the open cargo box formed therewith is to carry general payload items for transport. While the open pickup cargo box provides easy and convenient access to the bed for loading and unloading payload items, a number of pickup truck bed enclosures have been designed to cover the bed of the open cargo box of pickup trucks. The purpose of these designs is to form an enclosed and lockable compartment in conjunction with the cargo box and its bed. Motivations for employing cargo box enclosures include, but are not limited to, securing personal and payload items against theft, as well as preventing exposure of such items to the elements.
One common vehicle cargo bed enclosure is known as a “tonneau cover”. Tonneau covers are typically made of vinyl, fiberglass or aluminum, are flat and fit flush with the top of the vertical wall members that extend up from the bed of a vehicle such as a pickup truck, thereby defining the cargo box. Retractable tonneau covers are designed to provide easy access to the vehicle bed for loading and unloading. With respect to one such design, the tonneau cover deploys from, and then rolls back up into a canister, much like a window shade. The canister is commonly installed at the cab end of the cargo box, and the tonneau cover is deployed from the canister toward the tailgate end of the cargo box. Other tonneau cover designs retract by either folding or tilting.
While tonneau covers can provide a secure and lockable compartment that also facilitates easy access to the cargo bed from above, one major downside to the retractable tonneau cover is that it cannot be employed to cover payload items that extend in height much above the top of the walls of the cargo box. Another is that even in its refracted state, a tonneau cover can take up a significant portion of the cargo space. The canister design discussed above takes up the same space, whether refracted or not.
A topper is another commonly employed design for enclosing the otherwise open bed of a vehicle such as a pickup truck. The main structure of a topper is typically made of fiberglass or aluminum and typically mounts atop the walls extending vertically from the vehicle bed to form the cargo box. Toppers typically cover the entire cargo box to provide a secure and lockable compartment. One advantage of the vehicle topper over the tonneau cover is that it can accommodate payloads that extend vertically well above the top of the vehicle's cargo box. The height of some topper designs can even extend vertically above the top of the vehicle's passenger cab.
One disadvantage of the vehicle topper, however, is that loading and unloading large and/or bulky items can be made difficult. Access to the enclosed cargo compartment created by the topper is typically limited to a door at the tailgate end of the cargo box, or possibly through window/panel openings formed in the sides of the topper. Thus, many items that would have been more easily loaded into an open vehicle bed from above, must now be slid into the compartment through the rear door or the side openings. Even if the payload item(s) can be loaded through the back door or through the side openings, the person loading the vehicle is often required to crawl into the compartment on their hands and knees to adjust the enclosed load, as topper's are not typically configured with sufficient vertical clearance for someone to stand upright while inside the compartment.
Another disadvantage of known vehicle toppers is that even with an extended height advantage over known tonneau covers, they will not accommodate all payloads that might otherwise be encountered by a vehicle that has no vehicle topper installed. When such items cannot be accommodated by the topper, or cannot be easily loaded with the topper in place, the topper must be completely removed to accommodate such a payload Even if a. topper could be configured to include a removable roof, such configurations would be inconvenient to open and close. Moreover, such configurations would necessarily appropriate a significant amount of the storage space formed between the topper and the cargo box just to store the removed roof.